2 3b 1 3 5 July 8, 2019 16 32 64 128 2 3 7a 3b )+ 1 3 5a 4b 3b 2 1 3 2b 3 5 1 3 1 3b 1 5 2 5b 3 5 2 5•(-3b) 2 3-1 5